Drive mechanism



Dec.28,1937. D. R. DE TAR 2,103,517

DRIVE MECHANISM Filed Aug. 2, 1935 2 Sheets-Sheet '2 Inventor": DonaldR. De Tar.

His Attorney.

Patented Dec. 28, 1937 UNITED STATES PATENT OFFICE DRIVE IVIECHANISMDonald R. De Tar, Stratford, Conn, assignor to General Electric Company,a corporation of New York Application August 2, 1935, Serial No. 34,423

18 Claims.

My invention relates to drive mechanisms for use in the adjustment ofcircuit elements, such,

improved means whereby the speed at which the element to be controlledisvaried.

In variable speed drive mechanisms of the prior art it is necessary, inadjusting the speed ratio ofthe mechanism, to effect a selectiveoperation solely for the purpose of changing the speed ratio of thedevice. A further object of my invention is to provide means whereby thedesired speed ratio is automatically determined without any selectiveoperation, the desired'ratio being automatically chosen in response tothe range of movement of the control device.

Ordinarily reduction drive is desired only. for fine adjustment of thecircuit elements requiring relatively small movements of the controlmember, whereas a unity speed ratio is desirable to eflect largeradjustments of the circuit elements. In accordance with one form of myinvention the desired speed selection is, therefore, effected in,

response to the range of movement of the control member.

The novel features which I believe to be characteristic of my inventionare set forth with particularity in the appended claims. My inventionitself, however, both as to its organization and the method ofoperation, together with further objects and advantages thereof, willbest be understood by reference to the following specification taken inconnection with the accompanymg drawings in which Fig. 1 is adiagrammatic illustration of a tuning system in which my improvedcontrol device may be used: Fig. 2 is a side view partially in sectionillustrating one form of my improved control device; Fig. 3 is an endview of the device shown in Fig. 2; Figs. 4 and 5 are detail views ofcertain of the elements shown in Fig. 2; Figs. 6 and 7 illustrate thedetails of one form of direct drive coupling means constructed inaccordance with my invention and which may be applied to the controldevice shown in Fig. 2;Figs. 8 and 9. illustrate a modification of thecoupling means shown in Figs. 6 and 7;

and Figs. 10 and 11 illustrate an additional bodiment of my improvedcontrol device.

Referring to Fig. 1 of the drawings I have shown, by way of example, oneform of tuning arrangement in which my improved control device may beconveniently incorporated. The arrangement illustrated comprises atuning element shown in the form of a variable condenser I having arotor shaft 2 upon which is mounted a .pulley 3. A manually operablecontrol device 4 is arrangedto transmit rotation of its control shaft tothe pulley 3 by means of a cord 5 which traverses the pulley 3 and alsoa pulley on the control shaft of the device 4.

The tuning element I may form a part of a .radio receiving circuit as,for example, a variable condenser for tuning an input circuit to anydesired frequency. Although I have illustrated the device 4 ascontrolling a single element I, it will of course be understood that itmay be used to control a plurality of such elements in synchronism and,indeed, the latter is the usual arrangement. In the applicationmentioned it is desirable to provide suitable means for indicating tothe operator the frequency to which the set is tuned, in order that thetuning operation may be intelligently performed. In the arrangementillustrated this means comprises a pointer 8 mountedon the cord 5, whichcooperates with a scale I suitably calibrated to indicate the positionof the rotor shaft 2 following an adjustment thereof by the controldevice I. In order to maintain the pointer 6 in the correct positionwith respect to the scale I, an idler pulley 8 is provided over whichthe cord 5 extends.

In the operation of the above-described tuning system to adjust thetuning element I to the correct position such that the circuit in whichI the element is connected is correctly tuned to the desired frequency,the operating member of the device 4 is rotated to drive the pulley 3through the cord 5 until the correct adjustment is obtained. During suchrotation the pointer 8 moves along the scale 1 to indicate to theoperator the particular frequency or station to which the circuit isadjusted.

It is desirable in arrangements of the above character, in order quicklyand accurately to adjust the apparatus ,to the desired frequency, toprovide a control device l in which the control member may be drivenfrom the operating member at two different speeds.

I have illustrated in Figs. 2 and 3, a control device voi improvedconstruction having the desired dual speed operating characteristic. As

shown, the device comprises an operating member Qwhich is arrangedselectively to transmit rotary motion to a control member Ill, either ata reduced speed through a planetary reduction drive mechanism ordirectly through a direct drive coupling.

The reduction drive mechanism includes a plurality of balls or rollers Hpositioned between an inner raceway i2 provided in the shaft 9 and anouter stationary raceway formed by the members l3 and I4. Planetarymovement of the balls I I about the stationary outer raceway in responseto rotation of the shaft 9 causes rotation of the control member IDthrough the engagement of the balls H with the sides of peripheralopenings provided in the right tubular portion I 5 of the control memberi9. During such rotation of the shaft 9 to drive the member iii theinner and outer raceways are held in firm non-slipping engagement withthe balls by means of springs l6 and I! which bias the members l3 and I4together thereby to exert an inwardly directed component of force of theballs through the tapered bearing surfaces l8 and I9. A direct drivecoupling between the members 9 and It may be obtained by axiallyshifting the member 9 to the left to bring the ends of the arms 20 of aresilient U-shaped member 2| into engagement with the knurled surface 22of an annular member 23 mounted on the control member I0, and to releasethe balls l2 from engagement with the two raceways thereby to permit thesame to ride in the deep groove 24 provided in the shaft 9. With theelements in this position and during rotation of the shaft 9 a unityspeed ratio exists between the members 9 and Hi. It will, of course, beunderstood that with the elements in this position and in order totransmit movement between the operating and control members, theU-shaped member 2| must be fixedly secured to the shaft 9 and I haveshown such securing means as-comprising a nut 25 screwed onto thethreaded end of the shaft 9 and butting a lock washer 26 to press themember 2| into engagement with a stepped portion of the shaft.

The device described above may be mounted on a supporting wall 21 bymeans of the threaded extremity of a bearing member 29 and a nut 29. Afinger 20 is provided which passes through an opening in the wall 21 andextends into a slot provided in the spring l9 thereby to maintain theouter raceway stationary. The finger 30 includes an annular base portionwhich is pressed between the nut 29 and the wall 21. In order tofacilitate adjustment of the device a knob 3| is provided which ismounted on the left extremity of the operating shaft 9 by means of a setscrew 32. Motion may be transmitted from the control member ID to theelements to be adjusted by a cord positioned to ride in the V groove 33out in the member l9.

In the preferred construction of this embodiment of my improved controldevice the springs l9 and i! are of the form illustrated in Figs. 4 and5. As shown, each of the spring members It and I1 includes an annularportion 34 and spring arms 3! and 39. The annular portions 34 arefixedly mounted on steps 31 formed by re cesses in the members I 3 andI4. .As shown in Figs. 2 and 3 the arms 35 and the arms 36 of themembers It and I! are respectively biased toward each other and aresecured together at their ends by rivets 39 which extend throughopenings 39 in the ends of the arms. It will be seen that since each ofthe pairs of arms 35 and 36 are biased toward each other the taperedbearing surfaces will also be biased toward each other thereby to forcethe balls l2 into firm engagement with the inner and outer raceways.

By forming the outer raceway of the two solid annular members I3 and i4and employing the springs i6 and I! to bias the members toward eachother a rugged, economical structure is obtained which is easilyassembled and which is reliable in operation. Thus, the springs l6 andI! may be stamped from spring steel at a low cost. In addition, theruggedness of the members l3 and I4 resists wear caused by the planetarymotion of the balls about the tapered hearing surfaces i8 and i9.

From the foregoing description it will be observed that a speedselective operation is necessary to change the speed ratio between theoperating member 9 and the control member I 0. In the specific controldevice described this operation is carried out by axially shifting theoperating member 9 between its two operating positions.

In accordance with one feature of my invention means are providedwhereby no operation, independent of the tuning operation, is necessaryto change the speed ratio between the control and operating members. Oneembodiment of this means is shown in Figs. 6 and 7 as comprising afinger 42 mounted on one end of the shaft 9 by means of a nut 43 andlock-washer 44 and arranged to engage after a predetermined range ofmovement a cooperating finger 45 which is fixedly mounted on the controlmember ID. As shown in Fig. 7 the predetermined range of movementcorresponds to substantially one complete revolution of the shaft 9.

With the arrangement described in the preceding paragraph and in orderto secure a direct drive coupling between the members 9 and 10, it isonly necessary to rotate the shaft 9 in either direction until thefingers 42 and 45 engage each other. Following such engagement andduring further rotation of the shaft 9 in the same direction the controlmember ID is driven at the same speed as that of the shaft 9 until theapproximate desired adjustment of the apparatus being controlled isobtained. After the rough adjustment is completed a vernier or accurateadjustment may be secured by reversing the direction of rotation of theshaft 9 thereby to bring the reduction drive mechanism into action. If areduction drive arrangement of the type illustrated in Figs. 2 and 3 beemployed, it will be understood that a reversal of the direction ofrotation of the shaft 9 causes movement of the member [.0 through thereduction drive mechanism including the balls l8.

It will be observed that the range of movement of the shaft 9corresponding to a disengaged condition of the fingers 42 and 45 islimited to substantially one complete revolution of the shaft 9 which,of course, means that the range of reduction drive is also limited tosubstantially one revolution of the member 9. It follows that in orderto bring the elements of the control device to a position such that thereduction drive mechanism may be effectively utilized to perform theVernier adjustment, it is necessary to rotate the directly coupledmembers 9 and ID to a point slightly beyond the position correspondingto an exact adjustment of the apparatus being controlled.

In order to secure an increased operating range for the reduction drivemechanism, the embodiment ofmyjinvention illustrated in Figs; Sand 9 7may be emmoy at in this'embodiment a a ger 46 is fixedly mounted tntheoperating member 9 and is"*arrangedj to engage a finger I! whi rotatablymounted on the shaft9. Preferably the. "finger 4 3 a ab sl pported onthe Shaft 9 within the anriularrecessformed by'anannular member 48, thelatter member'being mounted on 10 i i i it T on the. finger "which isfixedly mountedon the the shaft 9 bya pin 49; "I'hefln ger .41is'ariarig'ed to engagelafter a predeterminedmovement therecontrolmembcrI II the rangeof movement being limited to: one revolution of thefinger. (1.. The

finger'lii is in turn arranged toengage thefinger 41 after a"predetermined amount of rotation limited to one revolution of the shaft9. 5

With the-elements of this embodiment of my 5 improved control device inthe" position shown'in Fig. '9; rotation of the shaft 9 in acounterclockwise direction through approximately one revolution bringsthe fingers l6 and I1 intoengagementgandiu'rther rotation "of the shaft9in' the same direction for slightly less than another j .revolutio ntime the fingers "and into en-U i tweenthemembersfi and'lfl. It willthusbe seen gagement to establish a direct drive coupling be-' thatjtheprovision r thethreeflngers operating to establish a direct'dri'vebetweenthe members connection betweenthe operating shaft'9 and the e Ch9 and III in the manner described, inereasesthe range of movement forthe reduced speed drive control member III to substantially; twocomplete revolutions of the shaft 9. O1 course, any desired number ofintermediate members, such as 41; may;

be employed therebyto increase the range of movement ofthe operatings'haft19 for'reductive. I driveand before direct drive at; unity ratioThe use in a tuning mechanism of the coupling arrangementillustrated inFigad and .7 or 8 and 9.

requires modification of theoontroldevice shown in Fig. 2only to'ltheextent indicatedin theseflgures, the portion oftheoperating"mechanism tothe left or the balls H being preciselyidentical w th thatshownfinFig.2.?Elements. 14,11 and 3T of Fig. 6 are not shown Hing-8101' simiplicity of the drawingbut it will, of course, be

cordingly I provide an annular member mount-j ed within the right end ofthe tubular portion 15 dfthe control member Ill. The member 50 is provided with anopening through which the shaft 9 extends and the end ofthis member forms astop forpreventing axial displacement of the shaft 9.

is apparent! inFig. 6 the modified direct drive coupling shown in thisfigure permits "the d'eepgroove of-Fig. 2 to be dispensed with since iit serves no useful purpose in the operation of the device. Intheoperationofsucha modified device and during rotation of the shaft todrive the control member [9 directly through the fingers 42 and 45, theballs I I" are 181539.11 times in' fric-' tional engagement with, andare caused toslip aboutgthe-bearingsurface of the outer raceway.

In order to retain the advantageous operating features of thedirectcouplin'g mechanism shown in Fig. 6 or8-and, at the'same'timeeliminate any friction between the componentparts of the mechanism whenthe device is being operated at either of its two speeds, thearrangement lilliistrated in Figs. IQ and 11 maybe employed. In thisembodiment offlmyinvention'the inner ball raceway is in the formfofatapered bearing surface 5| provided in the shaft 9 and theouterfstationary raceway comprises a solid annularjmember 82 which maybe supported from the wall 21 by brackets '59. A retaining ring "ismounted in :a groove in the operating shaft 9 in such a I position thata slightaxial movement of the shaft is peirnitted;"' As shown in Fig.10, the shaft 9is biasedlto the left by a spring member 59 which engagesat one end a pin 5'! provided at theright end of the shaft 9; the springmember being mounted on a support member 59 which is fixedly mounted onthe right. end of thecontrol'mem: ber'iO. l

The member 59 may be stamped fromh eavy sheet metalstock and, as shownin Fig. 11, is provided with an overturned portion 59 which extendsatright angles to the surfaceof the main portion of the member 58. Theoverturned por tion 59 is providedwith a pair of cam, surfaces 60 and GIwhich cooperate with a finger 92 mount-p shaft 9 to the right againstlthe bias of the spring 56 when the member! is rotated a sufficientamountin-either direction to cause the finger 92 to ride up one of thecam surfaces 60 or 6| Axial displacementof the shaft 9' tothe rightincreases the depth of the innerracewayby virtue of the taperedcharacteristic of the bearing surface II and thereby releases the ballsii from engagement with. the two vball racewaya The overturnedsegment 59ofthe member 5 9 .is provided with a lug or finger 99 at the apex of.the angle formed by the caml surfaces 50 and 8!. This finger 63cooperates with theffinger 62 to couple the members 9 and llilindirectdrive. relation when the two iinger's are in engagement.

In the operation of the above-describedeme bodiment of .my invention,rotation of the shaft- 9 in either direction for a predetermined amountcausesthe finger 92' to engage and ride overone of. the cam surfaces 69or 9! thereby automati-.

cally to shift the shaft! axially to the right against the bias of thespring member "to release the balls I] from theiinner and outer race;ways. Asthe finger 82 approaches the apex of theangle formed by the camsurfaces it engages the .iinger. 83 and couples-the members 9 and 10 indirect drive relation. Further rotation of the shaft9 in the samedirection causes the control ed on the operatingshaft 9 to shift axiallythe V member ID to be driven at the speed ofthe shaft it a 9.Durin'grotation of the shaft 9 to drive directly the control member ID,the balls ll are loosely held in. position between the inner and outerraceways and are free to rotate about the outer raceway withoutfrictionally engaging the inner raceway. i

1Withthe elements coupled in direct drive relation and, if it be desiredto'bring the reduction drive'mechanism into actiomit is only necessaryto reverse thedirection of rotation of the shaft 9 thereby to disengagethe flngerf 92 'from the fingerf 63 and the associated cam surfaceilor.6l and permit the spring 56 to move the shaft ate the left to bringthe balls H'lntoflrm en 'gagement withtheinner and outer raceways.

After this preliminary movement is complete the shaft 9 may be rotatedfurther in the same direce tion and the member'9 will drivethe member "Ithrough theballs ll included lnthe reduction drive mechanism. The rangeof movement for the reduction drive coupling is, of course, limited toaportion of a revolution of the shaft 9.

From the foregoing description it will be apparent that I havedevised animproved control device which may be embodied in a radio receiving setand which may be easily manipulated rapidly and accurately to tune theset to the desired signal frequency. Since the usual method of tuning areceiving system is that of tuning in one direction slightly beyond thepoint of maxi-'- mum response of the set to a selected frequency andthen tuning back'in the reverse direction-until the point of exactresponse is obtained, it will be seen that with my improved device thereduction drive mechanism automatically brought into action at thecorrect time and without any thought or skill on the part of theoperator.

' Thus, considering the tuning system illustrated in Fig. 1, if thetuning element I be adjusted so that the system in which it is connectedis tuned to a frequency corresponding to a pointer reading on the leftportion of the scale I and it be desired to. readjust the system toreceive a signal having a frequency indicated on the extreme rightportionof scale I, it is desirable to perform the rough adjustmentquickly and follow such'rough adjustment with a vernier adustment tosecure the desired exact tuning. The usual method of tuning includes aback and forth manipulation of the control device 4 after the roughadjustment is completed and in an attempt to obtain a maximum responseof the system being tuned to the desired signal frequency; It will beseen that it is advantageous to reduce the speed ratio between theoperating and control members when the first reversal of the directionof rotation of the operating member is performed. By using the directcoupling means illustrated in Figs. 6 to 9 inclusive in combination witha control device of the construction illustrated in Figs. 2 and 3 thecooperating fingers establish a unity drive speed ratio almostimmediately following rotation of the operating member to move thepointer 6 a substantial 'distance across the scale and during thepreliminary adjustment of the tuning elements. As the operator tunesthrough the desired signal frequency he naturally reverses the directionof rotation of the operating member to increase the selectivity ofresponse of the set. Such reversal of rotation causes disengagement ofthe fingers thereby automatically to bring the reduction drive mechanisminto action at the exact time that a reduced speed ratio is needed. Byincreasing the number of fingers employed in the manner illustrated inFigs. 8 and 9 the operating range of the reduced drive coupling may bemade sufficiently extensive to maintain a reduced speed ratio eventhough the rough adjustment is very carelessly performed. The provisionof the cooperating fingers mounted respectively onthe operating andcontrol members for efl'ecting dual speed control without a speedselective operation on the part of the apparatus being controlledrenders possible a quick transition from either speed ra-.

tio to the other without the slightest mechanical shock to theapparatus.

By using a device constructed in accordance with the embodiment of myinvention illustrated in Figs. 10 and 11 the above-noted advantage ofnon-selective and automatic speed change is obtained and at the sametime friction or drag between the component elements of the mechanism issubstantially eliminated. Thus, with the operating member 9 directlycoupled .to the control member in, the inner raceway is increased indepth so that the balls- II are loosely held in position and are free torotate when they come in contact with the outer raceway. Conversely,when the member Illv is being driven from the operating shaft 9 throughthe reduction drive mechanism, the fingers 62 and 63 are completelydisengaged. It should be noted that the amount of axialmovement of theshaft 9 resulting from movement of the finger 62 over either of the camsurfaces 60' or 6| prior to an engagement of the finger 62 with thefinger 63 is very small. This, of course, means that the appearance ofthe control panel is not marred by a noticeable extension of the controlshaft 9 from the surface of the panel.

My improved control device possesses a distinct advantage over the typeof dual control mechanisnr known to the art which includes separateoperating members for procuring the rough and fine adjustments. Thisadvantage resides in the elimination of unnecessary elements therebyresulting in a less expensive structure as well as a less complicatedvmode of operation.

It will be seen that in each of the various modifications of myinvention shown. the structure is of simple and rugged design. It willfurther be seen that back-lash and play, between the component parts ofthe device are completely eliminated, thereby assuring positive andreliable operation for a long period of use.

While I have described particular embodiments of my invention, it willof course be understood that I do not wish to ,be limited thereto sincemany modifications in the structure may be made,

and I contemplate by'the appended claims to cover all such modificationsas fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent in the UnitedStates is:

1. In combination, an adjustable element, a control member coupled todrive said element thereby to adjust said element, an operating member,means for coupling said control and operating members in reduced driverelation while said operating member is rotated over a pre' determinedrange in excess of one complete revolution, and means for automaticallycoupling said members in direct drive relation when said operatingmember is rotated in either direction to the limits of said range.

2. In combination, an adjustable element, a

control member coupled to 'drive said element thereby to adjust saidelement, an operating member, means for coupling said control andoperating members in reduced drive relation when said operating memberis rotated over a range corresponding to a predetermined number ofrevolutions of said operating member, and means for coupling saidmembers in direct drive relation when said operating member is rotatedin either direction to exceed said range, said last named meanscomprising a finger mounted on said .control member, a second fingerrotatably mounted on said operating member and arranged to engage saidfirst finger, and a third finger rigidly mounted on said operatingmemberand arranged to engage said second finger to move said second fingerinto engagement with said first finger after a predetermined movement ofsaid operating member.

3. In combination, a control member, an operraceway, means including aplurality of balls 15mg said balls from frictional engagement with saidraceways when said operating and control members are coupled in directdrive relation.

4.IIn combination, a control member, an operating member, an inner ballraceway arranged to f'be rotated with said operating member, an outerstationary raceway, means including a plurality j of balls ,positionedwithin said raceways for driving said control member from said operatingmember at a reduced speed, means for coupling L said control andoperating members in direct ,drive relation, a member mounted on saidcontrol member and provided with a cam surface, and meansincluding afinger mounted on said operating member and arranged to engage said camsurdrive relation.

face forfreleasingsaidballs from frictional engagement with saidraceways when said operating and control members are coupled in direct51 In combination, a control member, an operating member provided with aball raceway, a

' stationary ball raceway, means includinga pluralityof balls positionedwithin said raceways for driving said control member from said operatingmember at a reduced speed, means for coupling said operating and controlmembers in direct drive relation, a member mounted on said controlmember and provided with a cam surface, and means including a fingermounted on said operating member and arranged to engage said cam surfaceduring rotation of said operating member for releasing said balls fromfrictional engagement with said raceways when said operating and controlmembers are coupled in direct drive relation. l l

6. In combination, a control member, an operating member, a reductiondrive connection between said control member and said operating member,said connection including frictionally engaging surfaces, and meansresponsive to movement of said operating member through a predeterminedrange to release said frictionally engaging surfaces and to establish adirect drive connection between said members;

'7. In combination, a rotatable driven member, a rotatable drivingmember, an epicyclie driving connection between said driving member andsaid driven member whereby said driven member is rotated at a reducedrate of speed relative to the rotation of said driving member, saidconnection including a plurality of planetary members rotatable aboutthe axis of said driving member as a center, and means responsive torotation of. said driving member througha predetermined range toestablish a direct drive connection between said driving and said drivenmembers.

8. In combination, a rotatable driving member, a driven member, anintermediate member, means to drive the driven member by said drivingmember in a reduced speed relation through movement of said intermediatemember relative to both said driving and driven members, the

movement of the intermediate member being about the axis of the drivingmember as a center,

and means responsive to operation of the driving 1 member through apredetermined range to drive .the driven member at the same speed assaid driving member.

9. In combination, a driving member, a driven member, a ball and raceconnection between said membersto rotate said, driven member at a speedlower than the speed of-the driving member, and means, automaticallyeffective upon rotation of said driving member through a predeterminedrange to establish a direct drive connection between the driving anddriven members thereby to rotate the driven member at the same speed asthe drivingrnember.

10. In combination, a driving member, a driven member, a ball and raceconnection between said membersto rotate said driven memberat a speedlower than the speed of the drivingmember, and means automaticallyeffective upon'rotation of said driving member through a predeterminedrange to establish a direct drive connection between the driving anddriven members thereby to rotate the driven member at the same speed asthedriving member, and means to release said ball and race connectionwhen said direct drive connection is established.

1'1. Incombination, a drivingmembena driven member,.a ball and raceconnection between said members to rotate said driven member at a speedlowerthan the speed of the driving member, and a member operated by thedriving member and fmovable therewith to engage the driven memberinresponseto rotation of said driving member through a' predeterminedrange thereafter to rotate the driven member at the same rate as saiddriving member is rotated.

12. In combination, a driving member, a driven member, a ball and raceconnection between said members to rotate said driven member at a speedlower than the speedof the driving member, and a member operated by thedriving member and movable therewith to engage the driven member inresponse to rotation of said driving member through a predeterminedrange thereafter to rotatethe driven member at the same rate as saiddriving member is rotated, said members being soarranged that uponopposite movement of the driving member said last mem-' ber disengagesthe driven member and the driven member is driven only through said balland race connection.

13. In combination, a driving member, a driven member, an epicyclicconnection between said members to drive'said driven member at a speedlower than the speed of the driving member, and means to establish adirect drive connection between the driving and driven members when thedriving member is operated. to exceed a predetermined range thereby todrive the driven member at the same speed as the driving member, andmeans responsive to such operation of the driving memberto exceed saidpredetermined range to operate the driving member out from drivingradius at said point is smaller than said certain radius thereby tobreak the driving relation between said driving member and saidepicyclic driving means.

15. In combination, a rotatable driving member, a driven member, areduction drive connection between said members, means to establish adirect drive connection between said members in response to apredetermined movement of said driving member, and means to move saiddriving member longitudinally. of itself when said direct driveconnection is established and sufliciently to break said reduction driveconnection.

16. In combination, a rotatable driving member, a driven member, meansfor coupling said driving and driven members in direct drive relation,and means for establishing a reduced speed drive connection between saiddriving and driven members, said last-named means including a pluralityof balls engaging said driving member and movable about said drivingmember as a center, an inner raceway for said balls formed on thesurface of said driving member, an outer stationary raceway engagingsaid balls and comprising a pair of relatively movable annular membershaving tapered bearing surfaces, and a pair of spring membersrespectively secured to said annular members and having resilientportions biasing said annular members toward one another thereby toretain said balls in substantially non-slipping engagement with saidinner and outer raceways.

17. In combination, a rotatable driving member, a driven member, aconnection between said members to drive said driven member at a speedlower than the speed of the driving member, and means to establish adirect drive connection between the driving and driven members after thedriving member is rotated over a predetermined range in excess of onecomplete revolution, said last-named means comprising a first membermovable with said driving member, a second member movable with saiddriven member, and at least one intermediate member, said members beingconstructed and arranged to engage each other successively in responseto rotation of said driving member thereby to establish said directdriven connection between said driving and driven members after saiddriving member is rotated over said predetermined range.

18. In combination, an adjustable member, an operating member coupled todrive said adjustable member thereby to adjust the same, means forcoupling said adjustable and operating members in reduced drive relationwhen said operating member is rotated over a range corresponding to apredetermined rotation of said operating member, and means forestablishing a direct drive connection between said members, saidlastnamed means comprising a first intermediate member rotatable withrespect to said adjustable and operating members but arranged to makedriving engagement with said adjustable member upon being rotatedthrough a predetermined range in either direction, and a secondintermediate member movable with said operating member and arranged tomake driving engagement with said first intermediate member upon apredetermined rotation of said operating member in either direction.

DONALD R. DE TAR.

